Variations in landforms voer timescales Flashcards
What can change in seconds?
High-energy storm activity
Rapid mass movement
What can change in a seasonal period
Beach profile
What can change in a millennia
Sea-level change
High-energy storm events like tsunamis increase wave energy. What can this cause?
Removal of lots of beach sediment changing profile or removing all together
Destruction or breaching of sand dunes
Coastal flooding
What is rapid mass movement
Sudden rockfalls, land slides and slumps create changes in cliff-face profiles and retreating cliffs with the loss of land and possibly buildings
Examples of Summer (seasonal changes)
Fewer storms Less frequent high wind speeds Lower-energy waves Waves predominantly constructive Sediment is moved onshore, building up the beach increasing the gradient of the upper beach and forming a berm
What is a berm
A flat strip of land, raised bank, or terrace bordering a river or canal.
Examples of Winter (seasonal changes)
More storms high winds more frequently Higher-energy waves Destructive waves more frequent Sediment is moved offshore lowering the beach profile creating a steeper upper beach and a gentler lower beach
Eustatic changes over a millenia
Volume of water in oceans
If it’s a glaciation period more water gets frozen so less water in oceans
Global warming melting ice sheets = more water in oceans
Warming of oceans results in volume of water expanding = rise in sea level
Isostatic change
Localised change in the relative sea level cause by the upward or downward movement of land masses (Isostatic rebound)
During glacial periods weight of ice causes land to sink into the crust making sea levels appear higher. When the ice melts it causes the land to very slowly rise (Isostatic rebound)
What are the impacts of rising sea levels
Lower lying areas of coast flood
Deltas/spits/beaches disappear under water due to increased rates of erosion
River floodplains form a broad river estuary called a ria
If flooded valley is glaciated U shaped a fjord is formed
The shape of the valley means fjords are very deep
What is a ria
A ria is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea. Typically, rias have a dendritic, treelike outline although they can be straight and without significant branches.
What is a fjord
Geologically, a fjord or fiord is a long, narrow inlet with steep sides or cliffs, created by a glacier
What are the impacts of falling sea levels
Beaches no longer affected by waves and are left stranded above new sea level (raised beaches)
The former cliff line and landforms are left stranded as relict cliffs (no longer undercut and become covered in vegetation)
The wave-cut platform appears raised above new sea level to form a marine terrace.
These features can be found along the western coast of Scotland where the isostatic rebound is around 2mm a year
